My advisor has announced an intention to give a "rejection" talk to the lab sometime this summer. This may or may not be related to a post (on my personal blog) linking the intense need for a vacation and the series of rejections I've received this past year. I'd welcome a discussion, but I'm not sure a talk would help.
Being told that it's part of the process, that it's common even for the big names, is nothing new. Being told not to take it personally is besides the point. I have not been particularly attached to any of my rejected applications - I didn't really need funding/to attend a workshop/whatever; my motivation could easily be summed up as "that would be pretty cool". It just doesn't matter how unattached or thick-skinned you think you are; a rejection is a negative event that puts at least a small dent in your mood and casts a mild pall over all future attempts. Without some clear breeze of an acceptance to clear the air, future rejections just pile up, even over the course of a semester.
At a guess, my advisor has lost touch with the sensations of uninterrupted rejections. Congratulations are handed out to some people in the lab on a fairly regular basis, and they are all shared by the Head Honcho. The advisor gets some kudos on any accomplishment, that "look what we've done; it was a success!" Except that it's harder for a graduate student to share in the success of another grad student; it's more "look what they've done; so why can't my stuff get published?". The rejection train (hence the Schoolhouse Rock reference in the title) already pushed me into "I need a vacation"; even with this morale boost, I'm not sure how much more I can take before I cross the line into "Why bother?".
It's probably not about thick skin or detachment at all; it's about needing to be successful. People who want to go into academia will keep going despite rejection because they're determined to succeed. I don't have enough ambition to care about getting published or otherwise showing off my professional aspirations. The rejection may hit less, than if I thought these things were all important, but there's less reason to bounce back.